硅基三维集成微腔芯片非线性光学频率转换及纠缠光子对生成效应研究

Integrated entangled photon-pair source has aroused much attention in the field of quantum communication, which can be realized by a silicon nitride micro-resonator. Due to its low transmission loss and minimal nonlinear absorption, silicon nitride based integrated entangled photon-pair source is more superior in respect of energy consumption, device size, cost and performance. In this project, a three-dimensional integrated structure will be designed and fabricated, in order to improve the etching-caused waveguide distortion in the coupling area between the resonator and the waveguide for a two-dimensional planar structure, and overcome the technical limitation of high temperature annealing for achieving high quality factors. Based on a three-dimensional integrated structure, the resonator and waveguide can be fabricated separately, which can help to reduce the waveguide distortion and realize an accurate control of the coupling coefficient between the waveguide and the resonator. Combined with a transition film coating technique for reducing the waveguide scattering loss, a high quality factor cavity can be guaranteed, which is benefit for the integration with active functional devices. After studying the multi-layer coupling mechanism of the three-dimensional silicon nitride micro-resonator chip, this project aims to overcome the film thickness limitation in the three-dimensional integration, with the assistance of an ultrafast laser micromachining based material inner force releasing technique. Based on the developed silicon nitride chip, nonlinear optical frequency conversion and corresponding physical mechanism of nonlinear optics with few-photon sources will be studied, in order to reveal the interaction mechanism between photons and microring and explore its potential application in the generation of entangled photon pairs.

集成纠缠光子对光源芯片已成为量子通信技术发展热点之一，基于氮化硅这一硅基材料的微腔芯片可实现纠缠光子对的产生。由于具有低传输损耗、极小的非线性吸收等特性，其在尺寸、性能、能耗和成本等方面有较大优势。本项目拟设计并制备三维集成氮化硅微腔芯片，以改善二维结构中谐振腔与导光波导间的耦合区间隙在光刻与刻蚀过程中的畸变、克服高品质因子微环需高温退火处理的技术瓶颈。分层制备微腔与波导的三维集成结构，可有效降低波导畸变，精确控制波导和微腔间的耦合；结合降低波导表面散射的过渡膜技术，能有效保证谐振腔的高品质因子，有利于实现与有源功能器件的集成。在深入分析三维微腔多层耦合机制的基础上，本项目基于超短脉冲激光加工实现氮化硅膜应力释放，突破三维集成过程中的膜厚限制，研究其非线性光学频率转换效应，进一步探索少光子条件下的非线性光学相关物理机制，揭示光子与微环的相互作用机理，实现在纠缠光子对产生等方面的潜在应用。

氮化硅微环谐振腔芯片可用于实现纠缠光子对的生成，其具有低传输损耗、极小的非线性吸收等特性，在尺寸、性能、能耗和成本等方面有较大优势。本项目设计并制备三维集成氮化硅微腔芯片，以改善二维结构中谐振腔与导光波导间的耦合区间隙在光刻与刻蚀过程中的畸变、克服高品质因子微环需高温退火处理的技术瓶颈。分层制备微腔与波导的三维集成结构，可有效降低波导畸变，精确控制波导和微腔间的耦合；结合降低波导表面散射的过渡膜技术，能有效保证谐振腔的高品质因子，有利于实现与有源功能器件的集成。本项目以三维集成氮化硅波导平台开发为主要研究内容，针对常温条件下制备的氮化硅材料平台，实现了单层500纳米膜厚的氮化硅波导三维集成芯片的制备，解决了氮化硅波导芯片表面平坦化瓶颈，开发了一种基于等离子刻蚀工艺的表面平坦化处理技术的简易、高效、稳定的三维氮化硅集成工艺方法，为相关多维集成光电器件的发展提供强有力的平台保障。基于三维集成结构研制高品质因子的微腔芯片，实现的三维集成微环谐振腔芯片品质因子高于10000、厚膜微环谐振腔品质因子高于100000，基于相关微腔芯片完成了其非线性光学频率转换效应与宽带光频梳生成的研究及在量子纠缠光子对产生等方面的理论探索。在此基础上，进一步拓展了相关灵敏检测方向的实际应用。本项目有关三维集成氮化硅微腔芯片的研究成果，为低损耗、多功能集成光子器件提供了一个具有重大应用价值的波导平台，可用于高效的光学频率变换与宽谱光频梳生成等非线性光学效应相关研究，在量子光源等方面也有着潜在应用价值。